1. Field of the Invention
The present invention relates to a device for receiving video signals and to a method of controlling such a device.
2. Description of the Prior Art
To ensure their transport, whether through the air or by cable, video signals are generally modulated by a carrier at a given frequency which depends on the program concerned. The video signal is thereafter brought back to baseband by a tuner/demodulator assembly, also dubbed the front end. Various processing operations may thereafter be performed on the signals received by additional circuits as a function of the type of signal used.
When zapping from one program to another (hopping) at the request of the user, the tuner aligns itself to a new carrier frequency thereby bringing about the reception of a new signal and its possible processing by the additional circuits. In practice, these operations are not instantaneous and a noticeable time span may elapse between the user's command and the displaying of the new program.
If no particular measure is taken, the display screen shows nothing (“black screen”) during this span of time, this of course being prejudicial to the visual comfort of the user.
Solutions have already been proposed for attempting to remedy this drawback.
In patent applications EP 0 306 704 and JP 2000 032 338, it has been proposed that during a change of program a still image emanating from the initial program be displayed until the new program can be displayed. In patent application EP 0 712 242, it has been proposed that a predetermined still image be displayed.
In patent application WO 99/16 247, images of type I (intra coding images) contained in MPEG type streams corresponding to several programs are stored; during a change of program, if the new program is a program for which an image of type I is stored, this (still) image is displayed.
These solutions only slightly improve visual comfort for the user: admittedly they replace the black screen by a still image, but they do not in any way improve the fluidity of display.